Remove brake pads (section 17.2.1).
Remove the dust ring using a screwdriver.
Using the lever, push the piston all the way into the brake cylinder. Place a wooden gasket into the caliper cavity between the pistons and, holding it with your finger, press out the second piston with compressed air.
Remove the piston seal from the groove in the cylinder. Press out the second piston and remove the piston o-ring. On fig. 256 shows the piston and its details.
Pic. 256. Piston and its details.
1 - dustproof ring,
2 - sealing ring,
3 - piston,
4 - clamping ring.
Clean all parts thoroughly. All instructions for installing front wheel brakes (section 17.1.3) the same applies to the rear wheel brakes.
Lubricate the new O-rings and place them in the grooves of the brake cylinders.
Insert the pistons into the brake cylinders.
Use a template to check the position of the piston relative to the caliper, as shown in fig. 255. If necessary, turn the piston with tongs.
Pic. 255. Checking the position of the piston in the rear brake caliper (1) using a template (2).